Presettable signal seeking tuning system



Oct. 30, 1951 R. A. GULI.

PRESETTABLE SIGNAL SEEKING TUNING SYSTEM Filed Nov. 14,-Y 1947 INVENTORPatented Oct. 30, 1951 2.512.926.' l PRESE-'ETABLE SIGNAL S'EEKING:TUNING l -f SYSTEM Ber A- Gull, Buflaloifll- Y. assigner', hx mesne.assignmentsc S'ylyania Electric Products Inc.,

New York, N s etts Yg, 4a corporationof lt'lassachu-v Applicata ummm-14,muaslelriatuo.185,993.

'linie invention relates.. te. improvements in. sccahlled signal seekingreceivers.` 1n receiversof tnistvne, es is. Well liner/n.thetuninselenientis. meten driven and Scans, the. receiver Spectrumrepeatedly. When a. signal ofA predetermined Strength le. received. theinccnnns signal. itself eutuates mechanism te. Sluit. en .the runterdrive.. tnusleevins. the. receiver tuned.. te. the. incernins. Signal-Unner favorable. conditions... a. vervflerse-l nurnlier. ef. Stationsmay. be. receiv.e.d.,. which. means. that the listernerl may have.fiifncultv quickly finding.. the; particular. Station, to which.hevvishes te listen.

Surprise fer. example. that. the. listener'. desires tcnavefthe receiverSten.tunineionlyfenlccal. -t tiene and not.tc.stenen distantstatipne.the Sis-A nalS from which. may be. venian'` and. mure, sur iectte neise.

Intne past,r this has beenacccrnrlisnedbv auf justine the. sensitivityVcf.. the. central, tune.v which. Opensthe. motor circuit when.asisnalcf.- pre-- determined. Strengtn is received. but. this nut.altcsether Satisfactory. particularlr Wnen tlueref` ceiver.` is mountedin an.. automobile. becauset signal strength may. vary fronrtirrie. te.time and, asthe-carmcves about.

It. is an object. of tineini/.critic.n..nr-evereurnel this diflculty andto provide asisnalzseeking--re-- ceiver in` which the user may. nunkaIarrevluusr Selection and. calibrate the.; receiver tu-.respond only todesired stations. l

It.; is afurther obiectcf this.. invention torre.- vigie such; areceiver in which the, additional. Iap,- paratusrrequired te eivetneuser. thieme-Select.-

inay ability is relatively-Simple and inexperi.sive..l and-.introducesSubstantially n ccmnlicaticnsein.

thel receiver.

Still Other Objects and. advantages: ci; my. in vention will be apparentfrom the specification.

The features of novelty which Imbelieve; to be characteristic of myinventionare set forth withparticularty in the appended claims,Mylinvenf tionitself, howevenboth as to itsfundamental Principles and astoitsparticular embodiments., will best be understood by reference tothespeeication and accompanying drawing, in Vwhich Eigure 1 is-avschematic circuitdiagram of a signal seeking receiver in accordancewith Inyin-A vention,

Figure. 2 is` aplan View. of. the app arainisfuti-Y lized forpre-setting the. receiver to the.k desired` stations.

Referring now more particularly.to f.igure -1.01I the. drawing, I0designates theantenna ofA any.

suitable type, feeding radiorrequencyampler,

oscillator andconverter unit I I, containing the` tuned circuits,inductance I2 and' condenser I3, andimnductance I II and condenser I5.Additional tuned circuits may be employedl which, for the. sake orsimplicity, are not shown.

Tuning of these circuits may be by 'means` ol'` variable condensers or,preferably in the casei of an. automobile receiver, by permeabilitycores mqvablewithin the field ofinductances I2 and I4; rIfheyintermediate frequency output from the ain;- plirer, oscillator. andconverter unit. I I is supplied. to the4 intermediate frequencyamplifier I6. of usual construction and the output fromthis` is,vsuppliedJ to detector and. audio-amplifier unit I T.: thence toloudspeaker I8.

In. order to provide' the signal. seeking action,

of, thel receiver, apart, of the output of inter--l mediate frequencyamplifier I.6 ,is supplied to lim--v termediate frequency amplier isarranged to..

pass a. band Width of 5000 cycles, the narrow bandv selector 2.will bearranged to pass alhand` Width ofy approximately 500 cyclesor less.

Theeifect ofthis is torender the receiver rela. tively. insensitive. tonoise; that is to say, noise pulsesywill not cause4 the receiver, tostop scanning,

int'hegabsence of asignal.A

Thislpartcular feature is not, per se, apartof thisinvention, ,butisincluded merely. for. the pur-l l puse`V of completing the disclosureherein. TheT invention ofvthis featureis described andclaimed'l inthe.(2Q-pending application `of Verlis. H. Wiley,\ SerialfNo.. 5`54,4-'70,now United States Letters Patrv ent. No.v 2,4 919'42,` granted December-20, 1949..

Theoutput of.r the narrow. band selector. 2031s` pasidihrough; blocking.condenser 2AI- to the in. put. circuitofv tube 25, Tube 25 may be,forexample, atriode l having cathode,- 25e, control elecf trodem25g,and; anode, 25a.v The control electrode.-

2595,maybeconnectedrthrough resistor 22 from.l

tlieoutputrterminal .of condenser.v 2;I tothe tapofj potentioineter- 23Yenergized battery. 2.4:. and

connected. to. the lend from.l cathode. '2.5.0 totVv steunde. 'Ijh.foutent oi. tube-25 includesvv the. actuating;A Windinect-Sensitive-reina?whence-te xectcenn tact 29 of lock-in relay 3|, thencethrough armature contact 39 when relay 3| is closed and thence throughbattery l69 to ground. Armature 21 of relay 26 may be connected toground and when incontact with xed contact 28, is connectedthroughenergizing coil of lock-in relay 3| and battery 69 to ground.Also from the ener-V gizing coil of relay 3| there is provided a. manualstarting switch having movable contact 34 and' through any suitablemechanism, herein shown' and described as cam v42 driving follower 43which, in turn, moves the permeability cores or the variable condensers,and also the pre-.setting mechanism which will now be described.

From movable switch contact 34, there is provided a connection to fixedcontact 36 which is engaged by movable contact 31 carried on a bail bar39, pivoted at 39. The bail bar is also provided with a cam follower 49,as will be more particularly apparent from Figure 2. Bail bar' 38 ismoved by the traveling cams 49, 59, and each of which is mounted onadjusting screws 46, 41, and 48 respectively, driven by camr42 andsynchronized with the tuner carriage 43. Each of these cams 49, 59, and5|, carries a small raised portion adjacent to the center, as shown inFigure 2, so that upon passage of any cam under the cam follower 49, thebail bar will be Slightly lifted and contacts 31 and 36 opened. Theproportions of the cams 49, 59 and 5| and the cam follower 49 arepreferably so chosen that the contacts 36 and 31 are open over a rangenot exceeding kilocycles.

The operation of the receiver will nowY b e described. Assuming that thereceiver has been turned on, the tubes have warmed up, and the operatorwishes to tune to a station, he will momentarily close switch contact 34against fixed contact 35. This completes a circuit from ground throughbattery 69, energizing coil of lock-in relay 3 switch contacts 34 and 35back to ground,V

closing the lock-in relay 3|. Closure of lock-in relay 3| closesarmature contact 32 against fixedA contact 33, energizing the motorcircuit from battery 69, Vthe motor 4| will begin to operate, and thetuner will begin to scan. When a signal of predetermined strength istuned in, the output of the narrow band selector 29 which is rectied andapplied to the tube 25, in a manner to make the grid more negative withrespect to the'cathode, biases the tube to cut off or suciently nearthereto to permit the sensitive relay 26 to open.

If it were not for the provision of the pre-settableV apparatus, theAopening of the sensitive relay 26 wound interrupt the energizingcurrent of lock-in relay 3| and permit it to open, `thereby opening themotor circuit and stopping the scanning at that point.

However, it will be obcams 49, 59, and 5| which open contacts 36 and 31.

To make this more clear, consider that the cam carriage is at one end ofits travel and for purposes of clarity this may be assumed to be whenthe cam follower 49 is at the left hand side of the cam carriage inFigure 2. As the cam carriage moves to the left, cam 49 will approachlcam follower 49 and when it comes directly under open contacts 36 and31.

1 permits contacts 431 and 36 to close.

the camollower 49, will lift the bail bar 36 and As soon as it passesthis point Athe cam follower 49 rides down and They will remaincloseduntil' cam 59 engages cam follower 49 at which time the contactswill again be opened while cam 59 is passing under the follower y 49.-Afterthe passage of cam 59, the contacts 36 and 31. will again be closeduntil cam 5| en- A' gages follower 49, thereby opening contacts 31 rkwhich hel wishes to receive.

seen that although the sensitive relay 26 may open at any point in thetravel of the scanning process, the lock-in relay 3| will be held in andl and 36 while cam 5| passes under the cam follower 49. After the cam 5|has passed under the cam follower 49, the contacts will again close andwill remain closed until the cam carriage` reaches the end of its traveland is returned tov beginthetuning cycle again.

In order to calibrate or pre-set the apparatus, the user first, manuallytunes the desired station.

He will then adjust one of the cam screws 46, 41,f

or 48 until the corresponding cam is directly centered under the camfollower 49. This adjustment should be such that contacts 31 and36-willf be open over a range of a little less than 10,0009

In the arrangement herein shown I have indicated only three cams, thisproviding, of course,

' for the pre-setting of three stations. However, it

will`be understood that as many cams may be provided as desired so thatthe user may pre-set a receiver for any particular number of stationsThus it will be the-motor circuit will be kept closed except in theimmediate vicinity of the position for tuning stations which havealready been set up on the cams.

Inthe specification I have explained the principlesof? my invention andthe best mode in which I have contemplated applying those prinf ciples,sov as to distinguish my invention from otherinventions, and I haveparticularly pointed out and distinctly claimed the part, improvement orcombination which I claim as my invention or l discovery.A

served that the provision of this pre-settable ape` paratus provides analternative circuit for ener# gizing the lock-in relay 3| so that,aslong'as" contacts 36 and 31 are closed, the lock-in relay is held in andthe motor circuit is held'closed regardless of the position of relay26.' The function of contacts 36 and 31 is, therefore, to render themotor circuit independent of the operation of' the relay |26 except oversuch small segments of the scanning spectrum as Vmaybe set up by theWhile I have shown and described certain preferred embodiments of myinvention, it will be understood that modifications and changes may bemade without departing from the spirit and scope thereof, as will beclear to those skilled in the art;

1. Anv automatic tuning system comprising:

operating `frequency range;

tinuously anderepeatedly over'said tuning range;

acontrol system responsive to a predetermined. ,-amplitude vof signalenergy developed in a resonant 'circuit yofsaid apparatusfor'deeenergizing said power-operated means to terminate Variationthereby of said tuning means; and an auxiliary control system includinga longitudinally movable and longitudinally adjustable element actuated,in synchronized relation with the movement of said tuning means, over arange of movement; said auxiliary control system also including meansfor energizing said power-operated means independently of saidErst-mentioned control system except over a small portion of the rangeof movement of said element which small portion is established by thelongitudinal adjustment of said element and corresponds to an adjustmentof said tuning means in proximity to a preselected operating frequency.

2. An automatic tuning system comprising: variable tuning means fortuning a radio apparatus to any frequency within a predeterminedoperating frequency range; power-operated means energizable to vary saidtuning means continuously and repeatedly over said tuning range; acontrol system responsive to a predetermined amplitude of signal energydeveloped in a resonant circuit of said apparatus for de-energizing saidpower-operated means to terminate variation thereby of said tuningmeans; and an auxiliary control system including a plurality of elementsindividually adjustable longitudinally and simultaneously movablelongitudinally, in synchronized relation with the movement of saidtuning means, over a range of movement; said auxiliary control systemalso including means for energizing said power-operated meansindependently of said inst-mentioned control system except over a smallportion of the range of movement of each of said elements which smallportion is established by the longitudinal adjustment of said eachelement and corresponds to an individual adjustment of said tuning meansin proximity to a preselected operating frequency,

3. An automatic tuning system comprising: variable tuning means fortuning a radio apparatus to any frequency within a predeterminedoperating frequency range; power operated means energizable to vary saidtuning means continuously and repeatedly over said tuning range; acontrol system responsive to a predetermined amplitude of signal energydeveloped in a resonant circuit of said apparatus for de-energizing saidpower-operated means to terminate variation thereby of said tuningmeans; and an auxiliary control system including a plurality of camsindividually adjustable longitudinally and simultaneously movablelongitudinally, in synchronized relation with the movement of saidtuning means, over a range of cam movement; said auxiliary controlsystem also including a switch actuated by a plurality of cam followerelements, said switch being included in a circuit for energizing saidpower-operated means independently of said first-mentioned controlsystem except over a small portion of the range of movement of each ofsaid cams which small portion is established by the longitudinaladjustment of said each cam and corresponds to an individual adjustmentof said tuningr means in proximity to a preselected operating frequency.

ROY A. GULL.

REFERENCES CITED The following references are of record in the i'lle ofthis patent:

UNITED STATES PATENTS Number Name Date 1,700,282 Burns et al Jan. 29,1929 2,052,708 Hammond Sept. 1, 1936 2,231,806 Goldsborough Feb. 11,1941 2,453,252 .Newman afa- Nov. 9, 1948

